mpath: Update path in CheckPool function
mpath: Update path in CheckPool function

https://bugzilla.redhat.com/show_bug.cgi?id=1230664

Per the devmapper docs, use "/dev/mapper" or "/dev/dm-n" in order to
determine if a device is under control of DM Multipath.

So add "/dev/mapper" to the virFileExists, leaving the "/dev/mpath"
as a "legacy" option since it appears for a while it was the preferred
mechanism, but is no longer maintained

zippy2/libvirt,agx/libvirt,nertpinx/libvirt,datto/libvirt,nertpinx/libvirt,zippy2/libvirt,jardasgit/libvirt,fabianfreyer/libvirt,libvirt/libvirt,agx/libvirt,jfehlig/libvirt,nertpinx/libvirt,jardasgit/libvirt,eskultety/libvirt,fabianfreyer/libvirt,agx/libvirt,eskultety/libvirt,jfehlig/libvirt,jardasgit/libvirt,taget/libvirt,rlaager/libvirt,VenkatDatta/libvirt,crobinso/libvirt,VenkatDatta/libvirt,fabianfreyer/libvirt,agx/libvirt,VenkatDatta/libvirt,libvirt/libvirt,nertpinx/libvirt,crobinso/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,zippy2/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,eskultety/libvirt,taget/libvirt,olafhering/libvirt,eskultety/libvirt,taget/libvirt,taget/libvirt,jfehlig/libvirt,rlaager/libvirt,rlaager/libvirt,andreabolognani/libvirt,crobinso/libvirt,agx/libvirt,datto/libvirt,rlaager/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,datto/libvirt,fabianfreyer/libvirt,VenkatDatta/libvirt,rlaager/libvirt,taget/libvirt,eskultety/libvirt,andreabolognani/libvirt,datto/libvirt,zippy2/libvirt,libvirt/libvirt,olafhering/libvirt,crobinso/libvirt,nertpinx/libvirt,olafhering/libvirt,jfehlig/libvirt,jardasgit/libvirt,olafhering/libvirt,libvirt/libvirt,datto/libvirt